CRYSTAL-GROWTH AND PROPERTIES OF STRONTIUM TETRABORATE

Single crystals of strontium tetraborate SrO.2B2O3 (SBO) have been obt ained for the first time and their properties studied. The transparenc y range of SBO extends into the vacuum ultraviolet region to 130 nm, i n agreement with the ''anionic group'' theory. The near-IR transmissio n extends to 3.1 mum. SBO has a high effective non-linear optical coef ficient (d(eff)), comparable with KTP, an optical damage threshold exc eeding that of LBO (LiB3O5), high mechanical strength and it is not hy groscopic. Phase-matching does not occur in SBO for second harmonic ge neration.